High contrast, high capacity monobath processing method and composition for monochrome film

ABSTRACT

Improved monobath processing methods and compositions yielding high contrast and low fog in monochrome silver halide emulsion films while possessing high processing capacity. The monobath compositions contain two alkali agents and have a maximum of 40 grams of anhydrous sodium sulphite preservative per 1,000 milliliters of solvent. The invention is particularly advantageous for applications wherein film is used to record instrument data-readouts.

United States Patent [191 Speers Dec. 31, 1974 HIGH CONTRAST, HIGHCAPACITY MONOBATH PROCESSING METHOD AND [73] Assignee: General FilmDevelopment Corporation, Southport, Conn.

[22] Filed: Dec. 22, 1972 [21] Appl. No.: 317,763

[52] US. Cl. 96/61 M, 96/66 R, 96/66 HD, 96/66.3

[51] Int. Cl G036 5/38, G03c 5/30 [58] Field of Search.... 96/61 M, 66R, 66.3, 66 HD [56] References Cited UNITED STATES PATENTS 3,017,2701/1962 Tregillus et a1. 96/61 M 3,220,838 11/1965 Humphlett et a1. 96/61M 3,240,603 3/ 1966 Schuler et a]. 96/61 M 3,615,513 10/1971 Haist eta1. 3,705,806 12/1972 Sykes et a1. 96/61 M Primary ExaminerMary F.Kelley Attorney, Agent, or Firm-Bryan, Parmelee, Johnson 8L Bollinger 57 ABSTRACT Improved monobath processing methods and compositionsyielding-high contrast and low fog in monochrome silver halide emulsionfilms while possessing high processing capacity. The monobathcompositions contain two alkali agents and have a maximum of 40 grams ofanhydrous sodium sulphite preservative per 1,000 milliliters of solvent.The invention is particularly advantageous for applications wherein filmis used to record instrument data-readouts.

2 Claims, No Drawings HIGH CONTRAST, HIGH CAPACITY MONOBATH PROCESSINGMETHOD AND COMPOSITION FOR MONOCIIROME FILM BACKGROUND OF THE INVENTIONThis invention relates to combined developer-fixer photographicprocessing compositions, commonly known as monobaths, for monochromesilver halide emulsion films and, more particularly, to monobathcompositions producing high contrast images while exhibiting a highprocessing capacity.

An increasingly commercially important use of monochrome film of thesilver halide type is for recording and preserving data information.Thus, these films are often used to record the readings of instrumentdials, number registers, cathode ray tube displays, medicalinstrumentation displays and the like. In these and other applicationsit is often desirable for inspecting personnel to be able to examine thefilm as soon as possible after exposure for recording purposes.Therefore, in these instances, it is preferable that the film beprocessed in as short a time as possible. Additionally, since theinstruments photographed and inspecting personnel are often situated incommercial installations such as factories, plants, hospitals, and thelike, it is frequently necessary that the film be processed on site,under ordinary conditions, in as convenient and trouble free manner aspossible. Moreover, the exposed film should produce an image of highquality with good grain structure and contrast and little or no fog sothat an accurate and readily comprehensible reproduction of theinstrument readout is provided and preserved.

Conventional processing of such instrument recording film would requirea three or four-step photographic processing cycle that involves adeveloping solution, a stop bath, at fixing solution and a final wash.With conventional chemistry, the total processing time easily consumes10 to 30 minutes not including an additionaltime for washing. Althoughconventional time can be shortened by heating the solutions toaccelerate developing and fixing, such heating necessarily requiresclose monitoring of time and temperature. In addition, high temperatureprocessing reduces the active life of the developer and increases thedanger of fog in the finished product. Additives such as anti-foggingcompounds, hardeners and substances which reduce the swelling of thefilm gelatin arising from change of processing parameters to increasespeed can be added to conventional formulas. However, these result inincreased costs, complexity of the solution and nevertheless often failto satisfactorily reduce chemical fog and frequently reduce developerlife.

The present invention finds particular utilization in processingmonochrome silver halide emulsion films normally used in instrumentationapplications by providing monobath compositions which exhibit a highcapacity for development and short processing time while producing highcontrast with little or no fog. Monobaths have been commerciallyavailable from time to time, however, many are withdrawn because ofvarious shortcomings of the processing solutions. A comprehensivediscussion of monobaths, including representative formulations, ispresented in Monobath Manual, Grant Haist, Morgan & Morgan, Inc.,Hastings-on- Hudson, New York (1966). In my copending applications, Ser.No. 233,787, filed Mar. 10, 1972 now U.S. Pat. No. 3,819,378 for FineGrain High Speed Photographic Processing Monobath Composition andMethod, and Ser. No. 240,275, filed Mar. 31, 1972 now U.S. Pat. No.3,806,344 for Three Component Developer Photographic Processing Monobathcomposition and Method, I described generally the photographicprocessing behaviour of monobath compositions and the dependence ofimproved characteristics I and behaviour of the monobath upon the totalcomposition of solution rathen than upon the individual components. Thereader is referred to those applications, and those general observationsare incorporated herein for reference, for background information whichwill be of assistance in understanding the improved monobath compositionand method of the present invention. The monobath composition and methodof the present invention is yet a further improvement in monobaths andmonobath processing and is characterized by faster processing time,higher contrast in the developed image and a reduced tendency to producefog.

SUMMARY OF THE INVENTION The monobath processing method and compositionsof this invention achieve high contrast images in monochrome silverhalide emulsion films by providing a monobath containing both strong andweak alkali agents while limiting the amount of anhydrous sodiumsulphite preservative to a maximum of 40 grams per 1,000 milliliters ofsolvent. By providing such a composition, an image of higher contrastand reduced fog is obtained while fast processing time is maintained.Sludge and sediment may be kept low through the presence of additivesthus providing the solution with a long shelf and processing life.

Thus, it is an object of this invention to provide a high contrast, highcapacity monobath for silver halide emulsion monochrome films. A furtherobject of the invention is the provision of a monobath compositionhaving improved resistance to oxidation and sediment formation,resulting in increased processing life and long shelf life.

High contrast is particularly advantageous in silver halide films usedto record instrument data, especially so printed copies may then bereadily made by conventional electrostatic methods. Further, ininstrumentation applications, it is desirable to process the filmsrapidly for quick visual readout and as conveniently as possible so thatthey may be done on site either manually or in machines with a minimumnumber of steps and preferably under ambient room temperatureconditions.

Thus, it is yet a further object to this invention to provide amonochrome silver halide film monobath processing method and compositionwhich permits convenient and efficient high speed processing, eithermanually or by machine, of films used in instrument recordingapplications. Further objects and advantages of the invention will beapparent from the preferred embodiments thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The monobath processing methodand compositions according to this invention depart from the suggestedformulations of other experimenters. In the conventional approach tomonobath formulations, the developer concentration is upwards of fivetimes the amount required for a developer-only solution used in theconventional multi-step processing method. At the same time, the pH israised with a strong alkali such as sodium or potassium hydroxide andthe fixer, usually sodium thiosulphate, concentration is kept low inorder to yield the desired contrast. However, this approach results inlonger processing time since increasing the sodium thiosulphate fixercontent to reduce the time required for full processing undesirablyreduces the contrast of the film. Additionally, most formulators ofmonobath processing solutions teach the inclusion of the preservativesodium sulphite in an approximate amount of 50 grams anhydrous sodiumsulphite per 1,000 mulliliters of solvent, such as water, in thosemonobaths where the developer, such as hydroquinone(1,4-dihydroxybenzene), content is in excess. of 25 grams per 1,000milliliters.

In the monobath compositions of the present invention, 40 gramsanhydrous sodium sulphite per 1,000 milliliters water is the maximumamount of preservative, while 25 grams per 1,000 milliliters ispreferred. The amount of hydroquinone does not exceed 25 grams per 1,000milliliters water, while the preferred amount is lower.

l have found that monobaths having the following compositions haveexcellent keeping and exhaustion properties, produce little or no fogand are resistant to the formation of sludge or sediment even afterextensive use for processing. The monobath composition according to thisinvention is as follows:

The amount of anhydrous sodium sulphite used in the formula should bekept below 40 grams per 1,000 milliliters of solvent in order topreserve the high contrast and sharpness desired in the film image. Thesodium sulphite not only inhibits the atmospheric oxidation of thedeveloping agents but also plays an important part in the developingprocess by helping to remove products which would otherwise interferewith the controlled developing process. ln this instance, since theprimary developer is hydroquinone, the sulphite combines with quinonewhich is the oxidation product of hydroquinone to form a sulphonatewhich is a colorless, water soluble by-product that has little or noteffect upon the course of development. Bisulphites can be substitutedfor the sulphite, along with a corresponding increase in the amount ofalkali, however, such is to be done only in cases where it is desirableto concentrate the solution or to prepare the composition in twoseparate solutions.

Hydroquinone is the preferred developer since it is clean working andnon-staining and gives high contrast under rapid working conditions.l'lydroquinone maintains itself well in solution and has a slowexhaustion rate. When used in the amounts given above, it is notespecially temperature sensitive thus permitting a wider latitude to theuse of the monobath under ambient conditions such as room temperature.phenidone is included as a second developer in small amounts because itis superadditive with the hydroquinone, keeps well, has low toxicity andis fast working. Metol (lhydroxy-4-methylaminobenzene) may besubstituted for phenidone if the latter is not available, however, thisincreases the oxidation susceptibility of the composition and there is agreater tendency to produce excessive fog.

The presence of two alkali constituents in the monobath compositions ofthis invention is an important feature. The strong or caustic alkalisuch as sodium or potassium hydroxide provides energetic action givingmore rapid development and reduces the amount of alkali required.However, too much caustic alkali yields a solution of poor-keepingqualities. The use of a second alkali of the carbonate type, such assodium or potassium carbonate, permits the use of less caustic alkaliand at the same time preserves the useful life of the monobathcomposition over a greater length of time and reduces its exhaustionrate. The amount of alkali preferred is as given above, howeverincreasing the amount will provide greater contrast while decreasingamount will decrease the contrast.

The amount of sodium thiosulphate included in the composition isdependent upon the speed of clearing desired and the gamma'rangerequired. Increasing the amount of this fixing constituent speedsclearing but reduces the gamma range and the reverse holds. Since thegamma value of the film will be fixed by the composition in themonobath, best results are obtained using thepreferred amounts set forthabove.

Benzotriazole'is included in the composition as an anti-fogging agentwhich does not affect other properties of the developer. This compoundid particularly effective against fogging at elevated temperatures andwith extended processing times. Nitrobenzimidazole can be substitutedfor the benzotriazole, if desired. These agents are preferred over otheranti-foggants such as potassium bromide or potassium iodide since thelatter exhibit a restraining action on the developers. Sludge andsediment in the solution can be restricted by adding to the compositionEDTA Tetrasodium Salt, such as that available under the name Versene.While the former is preferred, also used may be sodium hexametaphosphateor ethylenediaminetetraacetic acid.

All constituents set forth herein are commercially available and thephotographic grade should be used unless other grades meet the requireddegree of purity. The water should be distilled, and preferablydeionized, water.

The following specific examples of monobath compositions of thisinvention will process monochrome silver halide film with a little of nofog and high contrast in the image being obtained. These monobathsolutions are resistant to the formation of sludge and sediment evenafter processing up to 10 rolls of -136 film of Kodak PLUS-X type intwenty ounces of solution.

EXAMPLE LCominued films at normal room temperature to obtain a highcontrast, low fog image, consisting essentially of the follow- MalerialAmount iriigleflonstltuents 1n the proportionate weight amountsPhenidone 0.5 g. g Benzotriazole 0.5 g. 5 EDTA Tetrasodium Salt 1.5 g. gSodium Thiosulphate 110 g. Material Parts by Weight Water 1000-1005Anhydrous Sodium Sulphite 15-40 Hydroquinone 9-25 EXAMPLE 2 10 Sodium orPotassium Hydroxide 3-8 Anhydrous Sodium or Potassium Carbonate 2-10Material Amount Phenidone 0.1-0.8

Benzotriazole 0-2 EDTA Tetrasodium Salt 0.5-3 Water 1000 ml.* AnhydrousSodium Sulphite 25 g. sodlum Thmsulphate 50425 Hydroquinone g. 15 SodiumHydroxide 6.5 g Anhydrous Sodium Carbonate 7.5 g Phenidone 04 g 2. Amethod for efficiently and permanently record Benzotriazole 0.6 g mg aninstrument reading occurring at a particular inggf g g zg g stant andmaking the reading nearly immediately availp g able in a formintelligently perceptible to the human Depending on the processingtemperature, 1000 milliliters of water constitutes eye comprising,exposing a monochrome silver halide moomos grams emulsion film to thereading to obtain an image thereof,

immersing the film in a monobath photographic propependntig on the i theabove cfomposltglons l cessing solution for approximately four to fiveminutes qulre pre erred delle Opment.nme of our We m at normal roomtemperature, the monobath composimes with fresh splutlon and hghtlylongel wlth tion consisting essentially of the following constituentsously used solutions. These times may be increased or in the toOrtionate Wei ht amounts iverr decreased by varying the fixer content.Recommended p p g g developing temperature is between 25 to 40C. Lowertemperatures increase, and higher temperatures de- Material P ns byWeight crease the processing time. The compositions will process filmsof Kodak PLUS-X and Kodak TRI-X types, mjg Sodium Sulphite {2925 as wellas high contrast copy films X-ray film instru- Hydroquinone 9-25mentation films. Because of their versatility these comiz g g i gggfifxt mggg fs Carbonate 3:? positions can be used to process films on siteimmediphenidone 0 g ately after they have been used to photographmstrugE g r San 8- B l' "lent fFadlngs' Sodium Thiosulphate 50-125 Iclaim: 1. A high capacity, high contrast monobath solution and obtaininga high contrast, low fog image thereon. for photographic processing ofsilver halide emulsion

1. A HIGH CAPACITY, HIGH CONTRAST MONOBATH SOLUTION FOR PHOTOGRAPHICPROCESSING OF SILVER HALIDE EMULSION FILMS AT NORMAL ROOM TEMPERATURE TOOBTAIN A HIGH CONTRAST, LOW FOG IMAGE, CONSISTING ESSENTIALLY OF THEFOLLOWING CONSISTUENTS IN THE PROPORTIONATE WEIGHT AMOUNT GIVEN:MATERIAL PARTS BY WEIGHT
 2. A method for efficiently and permanentlyrecording an instrument reading occurring at a particular instant andmaking the reading nearly immediately available in a form intelligentlyperceptible to the human eye comprising, exposing a monochrome silverhalide emulsion film to the reading to obtain an image thereof,immersing the film in a monobath photographic processing solution forapproximately four to five minutes at normal room temperature, themonobath composition consisting essentially of the followingconstituents in the proportionate weight amounts given: